In the process control industry, process facilities (e.g., a manufacturing plant or crude oil refinery, etc.) may be managed using distributed control systems. Contemporary control systems include numerous models tailored to control or monitor various associated processes of the facility. Conventional means link these modules together to produce the distributed nature of the control system. This affords increased performance and a capability to expand or reduce the control system to satisfy changing facility needs.
Field instruments may be used to obtain sensor readings or measurements of a particular characteristic (e.g., temperature, pressure, flow, sound, light) that is needed in the control system. Many prior art field instruments are configured as wired field instruments. This means that the field instrument is connected to the control system by conventional wiring. A wired field instrument sends sensor information to the control system over a conventional wired interface (e.g., a two wire twisted pair current loop).
As wireless technology has continued to become more available, wireless field instruments have become more commonly used in control systems. A wireless field instrument comprises transceiver circuitry that is capable of wirelessly transmitting sensor information to the control system. A wireless network may comprise a plurality of wireless field instruments. For example, a wireless network may be used to wirelessly transmit sensor information from various wireless field instruments in the wireless network to a global controller of the control system. A wireless field instrument may also be referred to as a wireless sensor.
When a wired field instrument is installed its location is well known. The wiring for the wired field instrument is and documented in wiring diagrams that describe the wiring, the junction box or termination information, and the exact location of the wired filed instrument. The same is not necessarily true for wireless sensors.
One of the benefits of wireless sensors is that they can be quickly deployed. One drawback of using wireless sensors, however, is that the exact location of the wireless sensor may not be sufficiently well documented or, if initially well documented, may be subsequently lost. Wireless sensors can be easily moved. Therefore, even if the exact location of a wireless sensor is initially known, subsequent movement of the wireless sensor may cause the location information of the wireless sensor to be lost. When the location information of the wireless sensor is lost it is easy to accidentally link the wireless sensor to a wrong location.
Therefore, it would be desirable to have an efficient system and method for providing a self-locating wireless sensor that has the capability of determining its location information and providing its location information to other units in a wireless sensor network.